Thermostatic apparatus.



Patented Feb. l3, I900.

1 r. WUODMAN. THERMOSTATIG APPARATUS.

(Applicatian filed. Marj28, 1899.)

(No Model.)

/m V a W UNITED STATES PATENT OFFICE.

EDXVARD F. WOODMAN, OF BOSTON, MASSACHUSETTS.

TH ERMOSTATIC APPARATUS.

SPECIFICATION forming part of Letters Patent No. 643,179, dated February 13, 1900.

Application filed March 28, 1899. Serial N0.7l0,753. (No model.)

To (tZZ whom it ntay concern/.-

Be it known that I, EDWARD F. WOODMAN, of Boston, county of Sufiolk, State of Massachusetts, have invented an Improvement in Thermostatic Circuit-Controlling Apparatus, of which the following description, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts.

This invention relates to that class of thermostatic circuit-controlling apparatus wherein the condition of an electric circuit is automatically changed by or through the disintegration of a fusible controlling device when the temperature in the vicinity of the apparatus has attained a predetermined point.

My present invention has for its object the production of a simple, strong, and efficient apparatus of the class described of cheap and durable construction, which will operate quicklyat a comparatively low temperature without the use of mercury, ether, or other volatile substances.

The apparatus may be regulated, as will be described hereinafter, to provide for the operation thereof at a desired temperature.

Figure 1 is a vertical sectional view of one form of thermostatic circuit-controlling apparatus embodying my invention on the line as :0, Fig. 3. Fig. 2 is a similar view on the line m 00, Fig. 3, showing the controller as partly fused or disintegrated. Fig. 3 is an under side view of the apparatus shown in Figs. 1 and 2, the circuit-terminals being shown in dotted lines. Fig. 4 is an enlarged perspective view of the fusible controller detached; and Figs. 5 and 6 are sectional views of modified forms of my invention, to be described.

The apparatus embodying my invention may be mounted on or supported by any suitable base of insulating material-such as porcelain, glass, &(3.=&11d I prefer to provide the base with a chamber in which the circuitchanging means are inclosed and protected from dust and moisture.

Referring to Figs. 1, 2, and 3, I have herein shown the base as composed of an attaching plate or block a, having in its face a circular depression a and provided with holes for screws 5 or other fastening devices by which a tight and strong closure.

the apparatus is secured to the ceiling or other portion of a room. In the recess a I insert the open end of a box I), of insulating material, provided with lateral ears or projections 19, through which suitable screws 3, Figs. 2 and 3, pass into the block a to securely connect the two parts, and, if desired, the space between the box I) and the wall of the recess a may be filled with cement to make The box is provided with suitable binding-posts b for the line-wires'L L, the inner ends of the post being electrically connected with terminals 0 0 within the box, which forms a tight chamber for the circuit-changing means.

By the term circuit-changing means I designate, broadly, a device or devices whereby the condition of the electric circuit can be changedas, for instance, from an open to a closed circuit, or vice versathe terminals 0 o forminga part of such means. These terminals are of suitable construction, usually made of strips of elastic or resilient metal, one or both of which under normal conditions are subjected to a flexing strain.

In Figs. 1 to 3 the apparatus is shown as adapted for use with a normally-open circuit. The bottom of the box or chamber b has a hole b through which is looselyinserted the controller d, herein shown as made wholly of h0- mogeneous fusible material, which is preferably cellular in form, or as a tube having a closed outer end, as at d, and having at its other end a laterally-extended lip or flange d which rests on the bottom of the chamber and supports the controller, the greater portion of the latter projecting beyond the base. Between the controller and the terminals I have interposed a detent, (shown in Fig. 1 as a spiral spring 8,) held under compression and act ing at one end against the terminal 0 to maintain it flexed and separated from the terminal c, the other end of the spring entering the cellular controller and bearing against the outer end thereof. When the parts are in this condition, it will be manifest that the electric circuit in which the circuit-changing means is included will be open at the termicircuit, which change in the condition of the latter may be made effective to give an alarm by any suitable mechanism. (Not shown.)

I have discovered that by making the controller wholly of fusible material and non-adherent to its support and preferably of cellular form a large area is exposed, to the action of heat, resultin in a much more rapid fusion or disintegration and at a lowertemperature than is now attainable with the use of fusible metal in other apparatus of this type.

I am not able to state absolutely why the operation of the apparatus embodying my invention is effected at a lower temperature than is the case with other apparatus in which the same fusiblematerial is used in a different way; but from my experiments and tests I believe the reasons to be substantially as follows: \Vhen the fusible material is used as solder to normally connect two pieces of metal by a joint, as has; been common heretofore, in all probability the solder when fused to unite the parts is affected thereby to form another alloy having a higher fusing-point than that of the solder itselfas, for instance, in uniting two pieces of copper the new or sub alloy formed would partake of some of the characteristics of the copper, oneof which is its comparatively high fusing-point. Again, when the fusible material thus forms a joint uniting two pieces of metal the latter serve to more rapidly convey heat away from the solder-joint, so that the latter will not absorb heat with sufficient rapidity to fuse it or cause disintegration until the surrounding temperature is much higher than the theoretical fusing-point of the solder.

Applyingeither hypothesis to my invention, a rational explanation is afforded of its operation at substantially the theoretical fusingpoint of the solder, for in my invention the solder is employed in the form of a controller complete in itself and resting loosely or detachably upon its support and non-adherent thereto.

Manifestly my controller is in no sense a joint, and hence there is no possibility of a suballoy being formed, and as there is no union of the controller with its support or any adherence thereto the support cannot operate to subtract heat from the controller when the surrounding temperature is raised.

I also overcome a most objectionable feature which arises after fusible-joint apparatus has been in use for some time-via, the disintegration, corrosion, or other change which takes place at the jointwhereby the latter becomes loosened and renders the apparatus useless, for it will be seen that I avoid the use of a joint of any kind, fusible or otherwise, the controller in-accordance with my invention being merelysupported by but nonadherent to the base of the apparatus.

As a result of my invention I have reduced the operating temperature of the apparatus to as low as 165 Fahrenheit, using the commercial fusible solder in making the controller, without any of the objectionable volatile or readily volatile substances which have heretofore been relied upon to effect a reduction of the temperature at which such apparatus will operate.

By varying the thickness of the walls of the controller I am enabled to vary the action of the apparatus, very thin walls tending to ef: fect fusion or disintegration of the controller at a lower temperature than when the walls are made thicker.

In operation when the temperature rises to the predetermined point the controller seems to disintegrate, granulate, or melt in such manner as to separate the bottom and the side walls, permitting the detent S to relax the strain :on the terminal with which it is en- To prevent displacement of the spring-detent, (shown in Fig. 1,) the terminal 0 may be provided on its under side with a stud or projectior c to enter the end of the detent.

The projecting controller may be protected from injury by downturned ears or guards b on the box portion 1) of the base, which extend somewhat beyond the plane of the outer end of the controller.

In the modification shown in Fig. 5 the base member a is omitted, but the circuit-changing means is adapted for a normally-closed circuit, the terminals t and '15 being normally held in engagement by the detent S shown as a spring under compression and held in operative position by the controller (1.

Obviously the detent need not be in the form of a spring, but it may be made in the form of a post or plug, as shown in Fig. 6. In said Fig. 6 the terminals m m are shown as normally separated by a detent in the form of a post, plug, or other device fof insulating material, the detent being normally maintained in operative position by the controller, as hereinbefser described, and such a detent could readily be used in the construction shown in Figs. 1 and 5.

My invention is not restricted to the precise construction and arrangement herein shown and described, nor is the form or construction of the base material, for various modifications or rearrangements may be made without departing from the spirit and scope of my invention. By supporting the con troller at one end and interposing the detent between its other end and the circuit-changing devices the thin walls of the controller are normally subjected to tensile strain, and so far as I am enabled to state at this time such tension on the particles of the metal constituting the controller tends to materially increase its sensitiveness and to make it more quickly responsive to a change in temperature of the air orother surrounding medium. The sensitiveness of the controller is also probably enhanced by the juxtaposition of a nonmetallic support therefor, such support being a relatively poor conductor of heat, and hence the heat will not be readily diffused from the controller.

Having described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. Athermostatic circuit-controlling device comprising circuit-changing means adapted to be included in an electric circuit, and a cellular controller for said means, said controller being composed of homogeneous fusible material and subjected to tensile strain.

2. A thermostatic circuit-controlling device comprising a base, circuit-changing means mounted upon it, and a tube-like controller for said means, composed of homogeneous fusible material and projecting out beyond the base, the controller loosely resting upon the latter and non-adherent thereto and provided with means whereby it may be subjected to tensile strain.

3. A thermostatic circuit-controlling device comprising circuit-changing means adapted to be included in an electric circuit, and a detachable controller therefor of fusible material, said controller being tubular and subjected to tensile strain, and non-adherently mounted upon its support to expose its outer end.

4. A thermostatic circuit-controlling device comprising an insulating-base, cooperating circuit'terminals mounted thereupon, a detent to maintain said terminals in normal position, and a cellular controller of homogeneous fusible material, subjected to tensile strain and detachably mounted on and loosely supported by the base and in engagement at its outer end with the detent, disintegration or fusion of said controller by a predetermined rise in temperature releasing the detent to thereby permit a change in the position of the circuit-terminals.

5. Athermostatic circuit-controlling device comprising a chambered base of insulating material, circuit-changing means contained within the chamber of the base, and a fusible, tube-like controller for said n1eans,closed at its outer end and projecting through a hole in the base, said controller loosely resting upon the base, and non-adherent thereto.

6. As a new article of manufacture, a tubular controller of homogeneous fusible material provided with a supporting-flange at one end, and at its other end provided with means whereby it may be subjected to tensile strain.

7. A thermostatic circuit-controllin g device comprising circuit-changing means adapted to be included in an electric circuit, a tubelike fusible controller therefor closed at its outer end and non-adherently mounted on its support, and a guard for the outer exposed end of the controller.

8. A thermostatic circuit-controlling device comprising circuit-changing means adapted to be included in an electric circuit, and a thin-walled cellular controller for said means, composed of homogeneous fusible material, the inner tubular surface thereof being out of contact with any metallic part or member of the circuit-controlling device.

9. A thermostatic circuit-controllin g device, comprising a base, circuitchanging means adapted to be included in an electric circuit, and a tubular controller for said means,composed of homogeneous fusible material and freely supported by the base, subjected to strain between its ends by the normal condition of the circuit-changing means, the major part of said controller being free from contact with any member or part of the circuit controlling device.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

EDWARD F. WOODMAN.

Vitnesses:

F. P. BUTMAN, JOHN C. EDWARDS. 

